Electrical switching circuits



Nov. 3, 1925. 1,559,802

G. H. STEVENSON ELECTRICAL SWITCHING CIRCUITS Filed May 16, 1921 //7 Van for: 660/ 6. /7. 57E/Q /750 7 7 A/ry.

Patented Nov. 3, 1925.

UNITED STATES PATENT OFFICE.-

GEORGE E. STEVENSON, F RYE, NEW YORK, ASSIGNOB TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

ELECTRICAL SWI'JXJHING CIRCUITS.

Application 'filed Kay 16, 1921. Serial No. 469,827.

To all whom it may concern:

Be it known that I, GEORGE H. STEVEN- SON, a subject of Great Britain, residing at Rye, in the county of Westchester, State of New York, have invented certain new and useful Improvements in Electrical Switching Circuits, of which the following is a full, clear, concise, and exact description.

This invention relates in general to electrical switching circuits, and more articu -larly to a switching circuit for e ectrical circuit characteristic changing devices.

The object of the invention is to provide a switching circuit to variously connect a plurality of such devices by means of which one of these is varied in increments disproportionate to the variations in the other.

This is accomplished by the invention in its preferred form in which a switch is provided to associate an inductance and a pair of condensers with a pair of leads for connection with an external circuit. The switch has a plurality of steps and at these steps simultaneously varies the inductance and the capacity in disproportionate increments.

The invention will be better understood by reference to the following specification taken in connection with the drawing which shows diagrammatically its preferred form, in which the circuit characteristic changing devices are combined to form a wavemeter.

A shaft 1 (dotted) rigidly supports three contact arms 2, 3 and 4 which when the shaft is turned, move together over their respective contacts. Contact arm 2 is provided with a short segmental contact 5 and a long contact 6. Contact arm 3 is provided with a long contact 7 and a short contact 8 similar to contacts 6 and 5, respectively, but positioned in reverse order. Contact arm 4 is provided with a series of contact posts 9, 10, 11, 12, 13, 11 which are connected to successivc equal sections of the inductance coil 15.

Two leads 16 and 17 are adapted to connect the apparatus with an external circuit. Lead 16 is connected with the contact arm 4, contact 8 and the stationary plates oi variable condenser 18. Lead 17 is connected with one end of the inductance coil 15, contact 7 and contact 6. Contact arm 3 is connected with the stationary ,.plates of variable air condenser 19. The movable plates of condenseis 18 and 19 are connected with the contact arm 2.

\Vith this arrangement of connections three arrangements of the condensers are possible, series, one alone, and parallel, depending upon the position to which the contact arms 2, 3 and 4 are turned. With the condensers 18 and 19. equal, the full capacity for the three positions will be in the proportion :1:2 respectively, and these will be their actual values in terms of the capacity of one of the condensers.

Calling the positions of the switch on contacts 9 to 1 1, the first to sixth steps, respectively, we have at the first and second steps small inductances shunted across the leads 16 and 17, the reactance of which may be balanced by varying the capacity of the condensers 18 and 19 between the limits zero and one-half the value of one of the condensers. With proportionately larger inductances of the coil 15 at the third and fourth steps of the switch, the bridging capacity of the condenser 18 may be varied from zero to its full value. At the fifth and sixth steps where the largest inductances are included, the full capacity of the condensers 18 and 19 in shunt are available. It will be noted that at the various steps the necessary fineness of capacity adjustment is obtainable since the range is merely changed in increasing proportions.

What is claimed is:

1. In combination, a line, an inductance and a pair of condensers arranged for connection across said line, and a multi-point switch for simultaneously varying the amounts of capacity and inductance included aross said line, said switch being arranged in one position to include across said line a relatively small amount of inductance and in parallel therewith said pair of condensers in series with each other, and in another position a larger amount of inductance across said line and in parallel therewith one only of said condensers, and in a third position a still larger amount of inductance across said line and in parallel tllileriewith both of said condensers in para e 2. In combination, a line, an inductance, and a pair of condensers arranged for connection across said line, a multi-point switch for simultaneously varying the amount of capacity and inductance included across said line, said switch being arranged in one position to include across said ine a relatively small amount of inductance and in parallel therewith said pair of condensers in series with each other, and in another position a larger amount of inductance across said line and in parallel therewith one only of said condensers, and in a third position a still larger amount of inductance across said line and in parallel therewith both of said condensers in parallel, and means independent of said switch for gradually varymg the capacity of said condensers.

3. An inductance, a system of condensers with common means for gradually varying their capacities, and switching means for connecting said condensers in various combinations in parallel with the inductance in a manner to make the variations in capacity produced by said varying means of greater magnitude for a given adjustment of the varyinglmeans when the inductance is large than w en it is small.

4. In combination, a plurality of condensers including adjusting means for varying their capaclty, a variable inductance, and a single operating member adapted to simultaneousl connect said condensers in various combinations in parallel with portions of said inductance, the variations of capacity of said condensers produced by a given movement of the ad usting means.

with different settings of said operating member being greater for a large amount of inductance connected in parallel with said condensers than for a smaller amount of inductance so connected.

In Witness whereof, I hereunto subscribe my name this 13th day of May A. D. 1921.

GEORGE H. STEVENSON. 

